The present invention relates to descent control devices and in particular to a device which is utilized to either allow a first person to lower another person, or object of great weight, from a place of height, in a controlled manner, or alternatively to allow a descender to lower himself or herself from a place of height.
Descent control devices, of various types, are well known and have been utilized as fire escape devices, as rappel devices for search and rescue teams, and as evacuation devices for leaving hovering aircraft such as helicopters. Although these devices have numerous designs, they are normally characterized by the following: (1) conventional devices are normally only easily utilizable by the person actually making the descent; and (2) rate of descent is normally controlled by the rate of movement of a brake along a rope or strap, the rope or strap being wrapped in a complex manner about the device so that resulting friction slows the rate of descent, with the amount of friction sometimes being adjustable.
Numerous problems have been associated with these conventional descent devices. First, they may be highly complex and difficult to set up in an emergency situation. Secondly, their complex nature may make them unusable without special training. Thirdly, when the device must be used repeatedly within a short period of time, such as during a fire, the conventional devices do not typically work well, since the device must be disattached from the end of the line, transferred to the beginning of the line, reattached to the line, and utilized again. Additionally, many of the devices are not sufficiently small and portable to be completely desirable as fire escape devices.
In the art of descent control devices, a primary consideration is safety. Preferred devices are those which are specifically designed to minimize jamming-up during operation, so that the person descending does not become stuck in mid-air part way through the descent, and so that the rate of descent can be easily controlled under almost every condition.
A major limitation to many conventional descent control devices, as eluded to above, is that they must be controlled by the person actually making the descent. Thus, objects, animals, invalids, unconscious persons and children often cannot be safely lowered by these devices. It is readily seen that a device which could be controlled by the person actually making the descent and alternatively which can also be controlled by another person, by making only a simple modification, for lowering an object, animal or other human descender, would be desirable.
With safety and emergency equipment, factors such as cost, portability, and size can become very important. If the equipment is too expensive, it will not typically be purchased, since consumers will often consider the probability of needing the equipment as being not worth the expense. Thus, when the emergency happens to them, they will have no proper equipment. If the device is not sufficiently portable, it cannot be rapidly moved to the location of use when needed. If the device is not suitably small, it might not be stored near those locations where it is most likely to be needed. It is readily seen that the more these features can be desirably improved, the better will be the descent control device.
Additionally, safety and emergency equipment should be relatively easy to use. During emergencies, the operator's attention is often divided between numerous concerns and rapid action is essential. Thus, the easier the equipment is to use, the higher the probability will be that it can serve its purpose. Additionally, the use of safety and emergency equipment is often only infrequently and insufficiently practiced. Therefore, the easier the equipment is to use, the more likely it will be that the user will remember its method of operation between uses. Further, it is best if one of ordinary intelligence can simply look at the equipment and figure out how to use it, having only seen the equipment in use once before or having never seen the equipment in use but rather only having had its use explained. Therefore, in this art, the more simple the device is or appears, the more desirable it may be as a descent control device. Thus, through a history of such devices, a trend toward simplifying improvements is observed.